In the past, subcutaneous implantation of solid preparations in the body has required surgery that takes a lot of labor and is accompanied by physical and mental sufferings and, occasionally, a surgical scar.
To solve such problems, some of the inventors have recently proposed a device for administering solid or semisolid preparations in the body through the skin, for example, in EP-A-139286 and Japanese patent applications laid-open Nos. 60-227772, 60-129057, 61-79470, 61-82761 and 61-180400. Such a device generally comprises a hollow needle and a plunger slidably arranged in the needle and, makes it possible to inject solid or semisolid preparations in the subcutaneous layers of a patient without performing any surgical operation. However, such a device makes it difficult to aseptically administer solid or semisolid preparations in the body.
To solve such a problem, the above inventors have proposed, in Japanese application Nos. 61-180398 and 61-180399 (corresponding to U.S. patent application Ser. No. 70429 and EP 87 11 0993), use of a device for subcutaneous implantation of solid preparations that comprises a hollow barrel with a capsule chamber, a hollow needle attached to the tip of the barrel, and a plunger slidably arranged in the barrel. Such a device may be used in combination with capsules containing solid or semisolid preparations and, the preparations are first ejected from the capsule by the plunger and then injected into the subcutaneous layers through the needle. Thus, such a device makes it possible to implant solid or semisolid preparations aseptically, but it also has some problems awaiting a solution. For example, when loading the capsule into the barrel, the operator is required to focus his concentration on an opening of the capsule chamber because of its small diameter. In addition, such a device requires prudent care to prevent the plunger from bending or breaking since the plunger is occasionally caught in the barrel.